Line of Duty: a handy catchup guide

Jed Mercurio’s police-corruption drama returns this week. Before the interrogation games begin, get up to speed with our refresher of the good guys, the double-crossers and the most bent cop in the force

Jed Mercurio’s addictive police-corruption drama returns for a third series on 24 March. It has been two years since we spent any time with the AC12 gang, so here’s a quick reminder what went down last time around.

The good guys

Headed up by Superintendent Ted Hastings (Adrian Dunbar), AC12 is an anti-corruption unit charged with investigating crimes committed by the police. The unit consists of Hastings, the slightly cocky Detective Sergeant Steve Arnott (Martin Compston) and the straight-talking Detective Constable Kate Fleming (Vicky McClure), who carries out most of the undercover work.

Anything else we should know about them?

It wouldn’t be a cop drama without flawed heroes. Hastings has huge debt problems, which he has hidden from his wife and which leaves him open to being blackmailed. Arnott (who, despite his baby face, has an incredible strike rate with the ladies) slept with one of the witnesses in a murder case, which also makes him a good target for blackmail. To make things worse, the murder victim was a fellow cop who worked with Arnott.

Fleming, meanwhile, was having an affair with the husband of series two’s first victim, Detective Sergeant Jane Akers, who was killed in a police ambush. It’s fair to say that no anti-corruption unit would employ any of them if their secrets came to light.

Refresh my memory about the last case ...

When we last hung out with AC12, they were investigating the fallout from the fatal ambush of a police convoy. The officer who arranged the operation, Inspector Lindsay Denton (Keeley Hawes), was immediately under suspicion: did she set up the ambush?

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After a great many twists, turns, red herrings and false leads, the controversial denouement of series two revealed that Denton was guilty – but for understandable reasons. Hoping to protect a vulnerable young woman, she had been dragged into a web of corruption and ended up taking the money to set up the ambush in the hope of claiming some autonomy in her own life.

Why exactly did the ambush occur?

Now, this is where it gets interesting. In 2012, series one introduced us to crazed Scottish crime boss, Tommy Hunter (Brian McCardie), a man with a penchant for adding bent coppers to his payroll. Most of that series centred on AC12’s investigation into whether Detective Chief Inspector Tony Gates (Lennie James), a man with a slightly too perfect clearance rate, was a corrupt cop.

It turned out he was not so much a bent cop as one who made a fatal error in sleeping with his former mistress, Jackie Laverty (Gina McKee), and spent the rest of the season paying the price for the fallout from that. However, Tommy did have a corrupt cop on his payroll – and that’s where the two series start to converge.

Tell me more …

That corrupt cop was a member of Gates’s team: one Detective Sergeant Matthew “Dot” Cotton (Craig Parkinson). In the series one finale, Dot was revealed to the audience – but not, crucially, to AC-12, as the bent cop working for Tommy. Gates died a hero. AC-12 moved on to pastures new. Still with me? Good. In series two, Tommy was in protective custody, and it transpired that the whole point of the ambush was to remove him from the game, thus keeping Dot’s cover as “the Caddy” safe.

Does that mean Dot is working for someone else?

He could be. Or he could have just seen a smart opportunity to get rid of the two people (Jane Akers being the other) who knew the truth about him.

What did he do next?

The great thing about Dot is that he’s two steps ahead of everyone else. He ended series two ensconced in AC-12 as their newest member. Yes, that’s right – AC-12, the anti-corruption unit, is employing the most corrupt copper in the force. This should prove interesting.

Anything else I should know?

Each series features a new “Big Bad”, ie a cop under investigation who may or may not be guilty (although it’s never as straightforward as that). This year, it’s Daniel Mays’s turn in the spotlight. He plays Sergeant Danny Waldron, the head of an armed response unit that finds itself in AC-12’s headlights when a straightforward callout goes fatally wrong. Let the interrogation games begin …